I'm curious. To those that are re-calibrating your gauges, how much variation are you experiencing? Especially, if you have much experience with the Park TM-1's.

Secondly, unless that variation is considerable, is it really of much concern?

My primary reason for initial use of a tension meter was to ensure even tension of spokes around a wheel and calibrate my fingers to what they were feeling. I know some like mrrabbit will have the finely calibrated fingers and ear to evenly tension a wheel by feel. But, my meter still suggests that it is more precise than my fingers or ear in this regard.

It seems that calibration wouldn't really be pertinent to tension equalization.

My second reason is to ensure I know to what absolute tension the wheel is built. Here I see the value to having a calibrated meter/interpretation card. But, a single point calibration isn't going to verify the meter against the range of the interpretation method. The first issue I see is the assumption that the spring rate will first be linear and then that it will remain so over its life. Any change in the spring rate over its range of travel and a multi point calibration for each gauge would be neccessary for modifying the interpretation chart.

If the spring rate is linear and isn't changing over the course of its life, then why can't we just zero the meter and know that the deflection will be accurate for the predetermined interpretation chart?